Natural Selection
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Natural Selection. Natural Selection:. A process by which characteristics that make an individual better suited to it's environment become more common in the species. Sometimes referred to as “survival of the fittest”. How Does Natural Selection work?.

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Natural Selection:

  • A process by which characteristics that make an individual better suited to it's environment become more common in the species.

  • Sometimes referred to as “survival of the fittest”


How does natural selection work
How Does Natural Selection work?

Those with the unique characteristics best suited for their environment will survive and produce offspring.

End result = ADAPTATIONS


English Peppered Moth –Natural selection in action

dark moth - random mutation

not as common

Soot covered tree

England 1800’s

camouflaged moth


Adaptations

  • Behaviors or physical characteristics that allow organisms to live successfully in their environment

Shell for protection

Long neck to reach leaves

Long shallow roots, needles to protect from animals


Niche

  • An organisms’ role in an ecosystem = niche.

  • Niche and Habitat are different

    • Address of an organism = Habitat

    • “Job” or “Profession” = Niche

Organism = tree

Habitat = Forest

Niche = produce oxygen

provide home for birds


Explain why two organisms cannot occupy the same niche:

  • If two species occupy the exact same niche in nature, one will die off due to competition for limited resources.


Video Link – Niche, Competition, Predation, and Symbiosis

http://www.youtube.com/watch?v=D1aRSeT-mQE



Competition:

  • The struggle between organisms to survive as they attempt to use the same limited resources.


Predation:

  • An interaction in which one organism kills another for food.


Predator or Prey:

  • Predator - organism that does the killing

  • Prey – organism that is killed.


Effect of predation on population size:

  • What variable is plotted on the x-axis? ______

  • What two variables are plotted on the y-axis? ________ and __________

years

# of moose

# of wolves


Effect of predation on population size:

  • How did the moose population change between 1965 and 1972 ___________

  • How did the wolf population change between 1973 and 1976? __________

It increased

It increased


Effect of predation on population size:

  • How might the change in moose population have lead to the change in wolf population?

    • The wolf preys on the moose so more moose meant more food for the wolf.


Effect of predation on population size:

  • How might disease in the wolf population one year affect the moose population the next year?

    • Disease in the wolf population might cause some to die. With less predators, the moose population would most likely increase.


Examples of Predator Adaptations

  • Cheetah speed

  • Owl eyes

  • Jelly fish venom


Defense Strategies of Prey

  • Mimicry

  • Protective Covering

  • False Coloring

  • Warning color

  • Camouflage


Video Link on Predator and Prey Interactions

http://www.youtube.com/watch?v=vZynrBA91fY



Symbiosis – a close relationship in nature that benefits at least one species

Bacteria from gut of termite

Termites


Symbiosis at least one species


Mutualism at least one species

  • Both species benefit


Commensalism at least one species

  • One species benefits, but the other isn’t harmed or helped.


Parasitism at least one species

  • One species benefits and the other is harmed.

  • The one benefiting is the parasite

  • The one being harmed is a host


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